Checkpatch.pl false positive? "ERROR: return is not a function, parentheses are not required"

Checkpatch.pl false positive? "ERROR: return is not a function, parentheses are not required"

[Olimpiu Pascariu]

Hi,

I've used checkpatch.pl to verify drivers/staging/dt3155/dt3155_isr.c,
in order to provide a patch which fixes the errors and warnings found by
checkpatch.
The script returns the following error:
ERROR: return is not a function, parentheses are not required
#155: FILE: staging/dt3155/dt3155_isr.c:155:
+  return (dt3155_fbuffer[m]->ready_head -

The original code is:

  return (dt3155_fbuffer[m]->ready_head -
           dt3155_fbuffer[m]->ready_len +
           dt3155_fbuffer[m]->nbuffers)%
          (dt3155_fbuffer[m]->nbuffers);

I've deleted the the first open parenthesis and the last close
parenthesis, and now the code looks like this:

  return (dt3155_fbuffer[m]->ready_head -
           dt3155_fbuffer[m]->ready_len +
           dt3155_fbuffer[m]->nbuffers)%
          (dt3155_fbuffer[m]->nbuffers);

IMHO the code is correct, though an auxiliary variable could be used to
avoid this error returned by checkpatch.pl. 

Regards,
Olimpiu Pascariu

Re: Checkpatch.pl false positive? "ERROR: return is not a function, parentheses are not required"

[Alexey Dobriyan]

On Sun, Mar 28, 2010 at 10:28:13PM +0300, Olimpiu Pascariu wrote:
> I've used checkpatch.pl to verify drivers/staging/dt3155/dt3155_isr.c,
> in order to provide a patch which fixes the errors and warnings found by
> checkpatch.
> The script returns the following error:
> ERROR: return is not a function, parentheses are not required
> #155: FILE: staging/dt3155/dt3155_isr.c:155:
> +  return (dt3155_fbuffer[m]->ready_head -
> 
> The original code is:
> 
>   return (dt3155_fbuffer[m]->ready_head -
>            dt3155_fbuffer[m]->ready_len +
>            dt3155_fbuffer[m]->nbuffers)%
>           (dt3155_fbuffer[m]->nbuffers);
> 
> I've deleted the the first open parenthesis and the last close
> parenthesis, and now the code looks like this:
> 
>   return (dt3155_fbuffer[m]->ready_head -
>            dt3155_fbuffer[m]->ready_len +
>            dt3155_fbuffer[m]->nbuffers)%
>           (dt3155_fbuffer[m]->nbuffers);
> 
> IMHO the code is correct, though an auxiliary variable could be used to
> avoid this error returned by checkpatch.pl. 

Yes, checkpatch.pl doesn't understand C.

Re: Checkpatch.pl false positive? "ERROR: return is not a function, parentheses are not required"

[Joe Perches]

On Sun, 2010-03-28 at 23:09 +0300, Alexey Dobriyan wrote:
> On Sun, Mar 28, 2010 at 10:28:13PM +0300, Olimpiu Pascariu wrote:
> >   return (dt3155_fbuffer[m]->ready_head -
> >            dt3155_fbuffer[m]->ready_len +
> >            dt3155_fbuffer[m]->nbuffers)%
> >           (dt3155_fbuffer[m]->nbuffers);
> > IMHO the code is correct, though an auxiliary variable could be used to
> > avoid this error returned by checkpatch.pl. 
> Yes, checkpatch.pl doesn't understand C.

And as currently implemented, can not.

I think this passes checkpatch without warning:

	return (dt3155_fbuffer[m]->ready_head -
		dt3155_fbuffer[m]->ready_len +
		dt3155_fbuffer[m]->nbuffers) %
	       dt3155_fbuffer[m]->nbuffers;

It might be better to use a temporary for dt3155_fbuffer[m]
so the code could look more like:
	return (p->ready_head - p->ready_len + p->nbuffers) % p->nbuffers;
	

Re: Checkpatch.pl false positive? "ERROR: return is not a function, parentheses are not required"

[Olimpiu Pascariu]

On Sun, 2010-03-28 at 12:59 -0700, Joe Perches wrote:
> I think this passes checkpatch without warning:

Yes, you are right.
Thank you.

Re: Checkpatch.pl false positive? "ERROR: return is not a function, parentheses are not required"

[Andy Whitcroft]

On Sun, Mar 28, 2010 at 10:28:13PM +0300, Olimpiu Pascariu wrote:
> Hi,
> 
> I've used checkpatch.pl to verify drivers/staging/dt3155/dt3155_isr.c,
> in order to provide a patch which fixes the errors and warnings found by
> checkpatch.
> The script returns the following error:
> ERROR: return is not a function, parentheses are not required
> #155: FILE: staging/dt3155/dt3155_isr.c:155:
> +  return (dt3155_fbuffer[m]->ready_head -
> 
> The original code is:
> 
>   return (dt3155_fbuffer[m]->ready_head -
>            dt3155_fbuffer[m]->ready_len +
>            dt3155_fbuffer[m]->nbuffers)%
>           (dt3155_fbuffer[m]->nbuffers);
> 
> I've deleted the the first open parenthesis and the last close
> parenthesis, and now the code looks like this:
> 
>   return (dt3155_fbuffer[m]->ready_head -
>            dt3155_fbuffer[m]->ready_len +
>            dt3155_fbuffer[m]->nbuffers)%
>           (dt3155_fbuffer[m]->nbuffers);
> 
> IMHO the code is correct, though an auxiliary variable could be used to
> avoid this error returned by checkpatch.pl. 

This code is indeed correct.  This is a bug in checkpatch, I think I
have sorted out the bug in the version below (which should be mirrored
out shortly).  If you could test the version below and let me know that
would be helpful:

  http://www.kernel.org/pub/linux/kernel/people/apw/checkpatch/checkpatch.pl-testing

-apw